Angie's List (ANGI) priced its offering of nearly 8.8 million shares at $13 each, the top of its range, late Wednesday. The stock began trading on the Nasdaq on Thursday and quickly rose to about $18 a share, but ended the day at $16.26 -- about a 25% gain from the IPO price. That gives the site a valuation of around $900 million.

The company was founded in 1995. At the ripe age of 16, it's much older than its fellow Internet companies that have recently gone public, including Groupon, LinkedIn and Pandora.

But like most of its younger IPO-ing peers, Angie's List is not profitable. In 2010, the company reported a $27.2 million net loss on sales of $59 million.

For the first nine months of 2011, Angie's List pulled down almost $62.6 million --- up from $42.9 million for the same period last year. But the company logged a $43.2 million loss at the same time, which is far steeper than its $19 million lost in the first nine months of 2010.

Angie's List has two revenue streams. When the site launches in a new area, it offers free memberships to attract new users and reviews. After about two years, the new market is converted to paid memberships, where readers have to pay to access reviews. An Angie's List representative said rates vary by market, but subscriptions cost an average of $6 per month.

The site is now in 175 paid membership markets in the U.S., and in October it passed the 1 million mark for paying members.

Angie's List also lets service providers who are highly rated by its members advertise discounts and other promotions on the site. As of September 30, more than 210,000 of the 815,000 service providers reviewed on Angie's List were eligible to advertise.

Only 10% of the eligible service providers were advertising as of September 30, but that business makes up most of Angie's List's revenue. In 2010, service providers paid $33.9 million and members paid $25.1 million in fees.

Busy 2011 for tech IPOs: This year has been chock-full of Internet IPOs -- many from companies that have spotty records of profitability.

This month shares of daily-deals site Groupon (GRPN) popped 31% in its debut, despite criticism for unorthodox accounting measures that led to several downward revisions of its financials. The IPO raised $700 million for Groupon's corporate coffers, making it the second-biggest tech IPO in history, behind the $1.7 billion Google (GOOG, Fortune 500) raised in 2004.

Professional networking site LinkedIn's (LNKD) shares more than doubled in its May IPO, even though the company turned only slight profits in 2010 and 2006 and has otherwise has been in the red every year since its 2003 inception. The stock is still trading well above its IPO price.

Earlier this month LinkedIn reported earnings that beat estimates, and raised its guidance for next quarter, but its shares still plunged 4.3% on news of a $500 million secondary offering.

Pandora (P) shares also fared well in its IPO, even though the company had warned investors that it expected to continue losing money "through at least fiscal 2012."

But last quarter, Pandora reported that it earned 2 cents per share on a non-GAAP basis, excluding stock-based compensation expenses. Using traditional accounting, Pandora lost $1.8 million for the quarter on sales of $67 million.